Question

Which one of the following can we do consciously with regard to breathing?

• A. One can breathe out air totally without oxygen.
• B. One can breathe out air through Eustachian tube by closing both nose and mouth.
• C. One can consciously breathe in and breathe out by moving the diaphragm alone, without moving the ribs at all.
• D. The lungs can be made fully empty by forcefully breathing out all air from them.

Answer 1

The correct option is B One can breathe out air through Eustachian tube by closing both nose and mouth.

During breathing, 20% oxygen is taken in and 15% oxygen is exhaled out. Movement of diaphragm is very important during breathing process. Ribs will also move in and out with the diaphragm. It is not possible to breathe by moving the diaphragm along without moving ribs. Even after forceful exhalation, lungs are never fully emptied. Residual volume, that is minimum amount of air in lungs always remain at all times. Eustachian tube connects middle ear cavity with nasopharynx and hence, one can breathe out air through it by closing both nose and mouth.

Thus, the correct answer is option B.